Advances in display technology have resulted in the implementation of touch screen displays as user interface mechanisms for various types of the electronic devices including mobile communications devices. In particular, touch screen displays have been utilized in cellular telephone applications, as well as tablet personal computer applications. As a part of the user interface of an electronic device, a touch screen display not only provides an output mechanism to the user by displaying images and/or text, but also receives input associated with a user's touching of the screen.
Touch screen displays allow for a more natural interface between a user and a device by adding increased convenience over a conventional keypad. Via a touch screen display, users often enjoy a more intuitive data input and output interface. Due to the intuitive nature of touch screen displays, developers of electronic devices are tending to incorporate touch screen technology into many applications where electronic devices are utilized, particularly in mobile device applications.
An evolving application for touch screen technology is within the realm of mathematic expression entry. The use of many non-touch screen keypad calculators introduces a disconnect between how a mathematical expression is written on a piece of paper, versus how a mathematical expression is entered into the calculator. Also, due to the limited number of keys on a keypad calculator, expression entry may be cumbersome and awkward for a user.